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TEST/DIAGNOSTIC PROCEDURES
(Continued)
SYSTEM-11 B MEMORY CHIP TEST.
A new feature is now included in the
Memory
Chip Test for System 11B. During power-up, the
CPU performs a self-testing routine. When all tests are satisfactory, the game proceeds to the
Attract Mode, allowing players to use the game. Whenever a portion of the testing does not
produce satisfactory results, the game displays a message, before proceeding to the next portion
of the testing. ONLY after all tests are satisfactory does the game allow play to begin.
In addition to the displayed message, when a test fails, LED2 ('DIAGNOSTIC') mounted on the CPU
Board can be observed to determine the probable cause of the problem. This LED blinks, or
flashes, a certain number of times to identify the probable cause, as described in the CPU LED
Indicator Codes Table. The operator can also start the self-testing routine by pressing the
CPU Diagnostic Switch (SW 2) on the edge of the CPU Board.
CPU LED Indicator Codes Table
Diagnostic LED
Blinksl
Display Message
Explanation
Flashes
1
U25 RAM FAILURE U25 RAM could not be used properly (NO other tests are performed;
the game is locked here, until the game is turned off).
2
MEM. PROT. FAILURE This message means that (A) the Coin Door may be shut; (8) the Mem-
ory Protect Switch may be stuck in the ON position; (C) the memory
prolect logic is protecting the memory; or (D) a U25 RAM failure is
occurring. (See Note 1)
3
U5t PIA FAILURE U5, has a malfunction. (See Note 2)
4 U38 PIA FAILURE U38 has a malfunction .(See Note 2)
5
U41 PIA FAILURE U41 has a malfunction. (See Note 2)
6
U42 PIA FAILURE U42 has a malfunction. (See Note 2)
7 U54 PIA FAILURE U54 has a mallunction. (See Note 2)
8
U,O PIA FAILURE UtO has a malfunction .(See Note 2)
9
IRO FAILURE
IRO has a malfunction. It may be missing or too fast or too slow .
10
U27 ROM FAILURE U27 'sinternal checksums do not match. It may be a ROM failure, or its
associated connections and connectingdevices Bre cBusing it to ap -
pear to have a problem. (The following U26 test Is skipped.)
11
U26 ROM FAILURE U26's internal checksums do not match.
Notes:
1 .
This test assumes that the Coin Door is
OPEN;
it is initiated ONLY by pressing the CPU
Diagnostic Switch (SW2).
2 . Altematively.
its associated connections or connecting devices arc causing the IC to ap-
pear to have problems .
SYSTEM-11 B SOUND CIRCUITRY TESTS.
Tests of the System-11B Sound circuitry, including the Audio Board, are possible only after
successful completion of the System-11B Memory Chip Test.
1 , Audio Board Test. A brief check 01 the Audio Board
(0-11581)
circuitry occurs at game
Turn-on; the game reports the test results by brief sounds, as follows: No sound
=
Audio
Board is not operating, or a failure is affecting the sound circuitry (broken cable; dead amplifier;
etc.): 1 sound
=
system OK; 2 sounds
=
RAM problem: 3 sounds
=
U4 problem; 4 sounds
=
U19 problem.
2. General System-11 B Sound Test. Press the Sound Diagnostic Switch (SW 1) on left
edge of the CPU Board. Listen for the two test sounds, showing that both the CVSD (Continu-
ously Variable Slope Delta) Modulator, which provides the voices for
TAXI,
and the DAC
(Digital-to-Analog Converter) sound circuits are functioning properly.
If no sound is heard, refer to the text entitled "NO SOUND ...". If
Q.il.e.
"ring" is heard, this
indicates a malfunction of the U23 RAM Chip. If either
l:i:lQ.
or
fQu.r
"rings" is heard, this indicates
a problem associated with the U21 ROM Chip. If either
mrea
or
1iY.e.
"rings" is heard, this
indicates a problem with the U22 ROM Chip.
TAXI 33